"It is unbelievably frustrating. The engine is in perfect condition it just needs water to keep cool enough.

Now captain what do you do????

To be fair I doubt I would have thought of his solution. But he did in the the most extreme conditions.
"

Me, I'd hook up the bilge pump to the raw water intake of the engine and open a seacock that would supply water to the bilge pump. Crack the **** (seacock, sorry censor software, didn't mean to offend) open enough to keep up with the engine requirements but not enough to flood the boat.

Finally a real sailor.
That is exactly what Glenn did!!
What a great idea especially since it worked for, I'm going on memory, a few weeks.